Fuel gauge system for measuring the amount of current in battery and portable electronic device including the same

ABSTRACT

A fuel gauge system for measuring the amount of current in a battery is provided. The fuel gauge system includes a first resistive element connected in series to the battery, a second resistive element connected in series to the first resistive element, a first switch connected in parallel to the second resistive element to control a current flowing in the second resistive element, a second switch connected in series to the second resistive element to control the current flowing in the second resistive element, a controller configured to output a first switching signal to the first switch and output a second switching signal to the second switch, and a fuel gauge circuit configured to measure a battery current flowing in the first resistive element and the second resistive element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119(a) from KoreanPatent Application No. 10-2015-0155318 filed on Nov. 5, 2015, thedisclosure of which is hereby incorporated by reference in its entirety.

BACKGROUND

Embodiments of the inventive concepts relate to a fuel gauge system, andmore particularly, to a fuel gauge system for measuring the amount ofcurrent in a battery using a plurality of resistive elements, and to aportable electronic device including the same.

Portable electronic devices using a battery as a power supply typicallyinclude a fuel gauge system which measures the amount of current in thebattery to estimate the state of charge of the battery. Conventionalfuel gauge systems use a method of measuring a voltage of one fixeddetection resistive element, and calculating the amount of current basedon the measured voltage.

When usual battery current (greater than several hundreds of mA) flows,a voltage applied across both ends of a detection resistive element isgreater than an offset voltage of a measurement circuit, so that theamount of current in a battery can be substantially accurately measuredusing a single fixed detection resistive element. However, when a microcurrent (less than about 1 mA) flows in a deep sleep mode, a voltage tobe measured decreases down to several tens of μV, and a measurementerror increases due to the offset voltage of the measurement circuit.

SUMMARY

According to some example embodiments of the inventive concepts, a fuelgauge system is configured to measure the amount of current in abattery. The fuel gauge system includes a first resistive elementconnected in series to the battery, a second resistive element connectedin series to the first resistive element, a first switch connected inparallel to the second resistive element to control a current flowing inthe second resistive element, a second switch connected in series to thesecond resistive element to control the current flowing in the secondresistive element, a controller configured to output a first switchingsignal to the first switch and output a second switching signal to thesecond switch, and a fuel gauge circuit configured to measure a batterycurrent flowing in the first resistive element and the second resistiveelement.

The first resistive element may be directly connected to the secondresistive element. The fuel gauge circuit may include an amplifierconfigured to sense potentials of both ends of the first and secondresistive elements and an analog-to-digital converter configured tooutput a digital signal based on a voltage difference received from theamplifier.

The battery may be placed between the first resistive element and thesecond resistive element. At this time, the fuel gauge circuit mayinclude a first amplifier configured to sense potentials of both ends ofthe first resistive element, a second amplifier configured to sensepotentials of both ends of the second resistive element, a firstanalog-to-digital converter configured to output a first digital signalbased on a first voltage difference received from the first amplifier,and a second analog-to-digital converter configured to output a seconddigital signal based on a second voltage difference received from thesecond amplifier.

The controller may enable the first switch and subsequently disable thesecond switch when the controller receives a mode signal correspondingto a first mode. The controller may enable the second switch afterwaiting for a desired, or alternatively predetermined time andsubsequently disable the first switch when the controller receives amode signal corresponding to a second mode.

The fuel gauge system may further include a level detector configured toreceive potential values of both ends of the first resistive element andpotential values of both ends of the second resistive element, to detecta level of the battery current, and to output the mode signal to thecontroller.

The fuel gauge circuit may further include a scaler configured to scalethe digital signal received from the analog-to-digital converteraccording to scaling information received from the controller. Thecontroller may output the scaling information that has been desired, oralternatively predetermined to the scaler according to the mode signal.

Alternatively, the fuel gauge system may further include a firstcharging circuit connected to the first switch and a second chargingcircuit connected to the first resistive element through a differentpath than the first charging circuit.

Other example embodiments of the inventive concepts relate to a portableelectronic device using a battery. The portable electronic deviceincludes a fuel gauge system configured to measure the amount of currentin the battery and a plurality of chips connected to the fuel gaugesystem.

Example embodiments of the inventive relate to a fuel gauge system formeasuring the amount of current in a battery. The fuel gauge systemincludes a first switch connected in series to the battery, a secondswitch connected in parallel to the first switch, a controllerconfigured to output a first switching signal to the first switch andoutput a second switching signal to the second switch, and a fuel gaugecircuit connected to both ends of the first switch. The first switch maybe a transistor that operates as a first resistor when it is enabled,and the second switch may be a transistor which functions as a secondresistor, having a greater resistance value than the first resistor,when it is enabled.

The fuel gauge circuit may include an amplifier configured to sensepotentials of both ends of the first switch and an analog-to-digitalconverter configured to output a digital signal based on a voltagedifference received from the amplifier.

According to some example embodiments of the inventive concepts, a fuelgauge system is comprising a first switch connected in series to a firstresistor and to a battery, and in parallel to a second resistor, asecond switch connected in series to the first and second resistors, andin parallel to the first switch, and a fuel gauge circuit connected inparallel to the first and second resistors and configured to measure abattery current flowing in the first resistor and in the secondresistor.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the inventive conceptswill become more apparent by describing in detail example embodimentsthereof with reference to the attached drawings in which:

FIG. 1 is a block diagram of a portable electronic device, according tosome embodiments of the inventive concepts;

FIG. 2 is a detailed block diagram of a fuel gauge system, according tosome embodiments of the inventive concepts;

FIG. 3 is a detailed block diagram of a fuel gauge system, according toother embodiments of the inventive concepts;

FIG. 4 is a timing chart showing the operation of the fuel gauge systemillustrated in FIG. 3;

FIG. 5 is a detailed block diagram of a fuel gauge system according toexample embodiments of the inventive concepts;

FIG. 6 is a detailed block diagram of a fuel gauge system, accordingexample embodiments of the inventive concepts; and

FIG. 7 is a detailed block diagram of a fuel gauge system, according toexample embodiments of the inventive concepts.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The inventive concepts now will be described more fully hereinafter withreference to the accompanying drawings, in which example embodiments.The various embodiments may, however, be embodied in many differentforms and should not be construed as limited to the example embodimentsset forth herein. Rather, these example embodiments are provided so thatthis disclosure will be thorough and complete, and will fully convey thescope of the embodiments to those skilled in the art. In the drawings,the size and relative sizes of layers and regions may be exaggerated forclarity. Like numbers refer to like elements throughout.

It will be understood that when an element is referred to as being “on,”“connected” or “coupled” to another element, it can be directly on,connected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyon,” “directly connected” or “directly coupled” to another element,there are no intervening elements present. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items and may be abbreviated as “/”.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another. For example, a first signal could be termed asecond signal, and, similarly, a second signal could be termed a firstsignal without departing from the teachings of the disclosure.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the variousembodiments. As used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” or “includes” and/or “including” whenused in this specification, specify the presence of stated features,regions, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one or more other features,regions, integers, steps, operations, elements, components, and/orgroups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which the various embodiments belong. Itwill be further understood that terms, such as those defined in commonlyused dictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and/orthe present application, and will not be interpreted in an idealized oroverly formal sense unless expressly so defined herein.

In the drawing figures, the dimensions of layers and regions may beexaggerated for clarity of illustration. Like reference numerals referto like elements throughout. The same reference numbers indicate thesame components throughout the specification.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the example term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

Example embodiments are described herein with reference tocross-sectional illustrations that are schematic illustrations ofidealized embodiments (and intermediate structures) of exampleembodiments. As such, variations from the shapes of the illustrations asa result, for example, of manufacturing techniques and/or tolerances,are to be expected. Thus, example embodiments should not be construed aslimited to the particular shapes of regions illustrated herein but areto include deviations in shapes that result, for example, frommanufacturing. For example, an implanted region illustrated as arectangle will, typically, have rounded or curved features and/or agradient of implant concentration at its edges rather than a binarychange from implanted to non-implanted region. Likewise, a buried regionformed by implantation may result in some implantation in the regionbetween the buried region and the surface through which the implantationtakes place. Thus, the regions illustrated in the figures are schematicin nature and their shapes are not intended to illustrate the actualshape of a region of a device and are not intended to limit the scope ofexample embodiments.

When the terms “about” or “substantially” are used in this specificationin connection with a numerical value, it is intended that the associatednumerical value include a tolerance of ±10% around the stated numericalvalue. Moreover, when reference is made to percentages in thisspecification, it is intended that those percentages are based onweight, i.e., weight percentages. The expression “up to” includesamounts of zero to the expressed upper limit and all valuestherebetween. When ranges are specified, the range includes all valuestherebetween such as increments of 0.1%. Moreover, when the words“generally” and “substantially” are used in connection with geometricshapes, it is intended that precision of the geometric shape is notrequired but that latitude for the shape is within the scope of thedisclosure. Although the tubular elements of the embodiments may becylindrical, other tubular cross-sectional forms are contemplated, suchas square, rectangular, oval, triangular and others.

Although corresponding plan views and/or perspective views of somecross-sectional view(s) may not be shown, the cross-sectional view(s) ofdevice structures illustrated herein provide support for a plurality ofdevice structures that extend along two different directions as would beillustrated in a plan view, and/or in three different directions aswould be illustrated in a perspective view. The two different directionsmay or may not be orthogonal to each other. The three differentdirections may include a third direction that may be orthogonal to thetwo different directions. The plurality of device structures may beintegrated in a same electronic device. For example, when a devicestructure (e.g., a memory cell structure or a transistor structure) isillustrated in a cross-sectional view, an electronic device may includea plurality of the device structures (e.g., memory cell structures ortransistor structures), as would be illustrated by a plan view of theelectronic device. The plurality of device structures may be arranged inan array and/or in a two-dimensional pattern.

FIG. 1 is a block diagram of a portable electronic device 10 accordingto some example embodiments of the inventive concepts. The portableelectronic device 10 may include a fuel gauge system 100 and a pluralityof chips 200. The portable electronic device 10 may be implemented,e.g., as a laptop computer, a cellular phone, a smart phone, a tabletpersonal computer (PC), a personal digital assistant (PDA), anenterprise digital assistant (EDA), a digital still camera, a digitalvideo camera, a portable multimedia player (PMP), a personal navigationdevice or portable navigation device (PND), a handheld game console, amobile internet device (MID), a wearable computer, an internet of things(IoT) device, an internet of everything (IoE) device, a drone, or ane-book.

The fuel gauge system 100 may measure the amount of current in a batteryof the portable electronic device 10 which includes a battery powersupply. The plurality of chips 200 may include, e.g., a centralprocessing unit (CPU), a graphics processing unit (GPU), an applicationprocessor (AP), a memory device, a display device, a sound unit, acommunication module, an interface, and so on, which are provided withpower by the battery.

FIG. 2 is a detailed block diagram of the fuel gauge system 100according to some example embodiments of the inventive concepts.Referring to FIG. 2, the fuel gauge system 100 may include a firstresistive element 115 (R1), a second resistive element 125 (R2), a firstswitch 110, a second switch 120, a controller 140, a fuel gauge circuit150, and a charging circuit 180. The fuel gauge system 100 may alsoinclude a battery 130.

The first resistive element 115 may be or include a resistor used tomeasure a charge/discharge current (hereinafter, referred to as abattery current) which flows out of or into the battery 130.Hereinafter, the battery current will be restrictedly described as adischarge current of the battery 130 for convenience' sake in thedescription. However, the fuel gauge system 100 may also perform thesame function during charge with the direction of battery current set inreverse.

The first resistive element 115 may be connected, for example directlyconnected, in series to the battery 130. The fuel gauge circuit 150 maybe connected to a node (hereinafter, referred to as a battery node) NBto which the first resistive element 115 and the battery 130 areconnected. When battery current flows through the first resistiveelement 115 connected in series to the battery 130, a first potentialdifference V1 is created that is proportional to a battery current Ibatand a resistance value R1 of the first resistive element 115. Forexample, the first potential difference V1 can be calculated usingEquation 1:V1=Ibat*R1.  (1)

The second resistive element 125 may be an auxiliary resistor used tomeasure a battery current. The second resistive element 125 may beconnected, for example directly connected, in series to the firstresistive element 115. The second resistive element 125 may have agreater resistance value than the first resistive element 115.

When a battery current flows through the first resistive element 115 andthe second resistive element 125, which are connected in series to thebattery 130, a second potential difference V2 may be created that isproportional to the battery current Ibat, the resistance value R1 of thefirst resistive element 115, and the resistance value of the secondresistive element 125. For example, the second potential difference V2can be calculated using Equation 2:V2=Ibat*(R1+R2).  (2)

The first switch 110 may be connected in parallel to the secondresistive element 125 to control a battery current flowing in the secondresistive element 125. The second switch 120 may be connected in seriesto the second resistive element 125 to control the battery currentflowing in the second resistive element 125. The first switch 110 andthe second switch 120 may be or include a complementary metal-oxidesemiconductor (CMOS), a field effect transistor (FET), or a bipolarjunction transistor (BJT).

The first switch 110 may be enabled when a first switching signal Q1 islow. The second switch 120 may be enabled when a second switching signalQ2 is low. In other words, when the first switch 110 is disabled and thesecond switch 120 is enabled, a battery current may flow in the secondresistive element 125. Contrarily, when the first switch 110 is enabledand the second switch 120 is disabled, a battery current may not flow inthe second resistive element 125.

The controller 140 may output the first switching signal Q1 to the firstswitch 110 and the second switching signal Q2 to the second switch 120to control the turning on/off of the first and second switches 110 and120 for a substantially accurate measurement of battery current. Thecontroller 140 may receive a mode signal MS from an AP (not shown) or aplatform logic (not shown).

The mode signal MS may indicate a first mode when MS is low and mayindicate a second mode when MS is high. The mode signal MS may include afirst mode signal indicating the first mode or a second mode signalindicating the second mode. The inventive concepts are not restricted tothe example embodiments and the mode signal MS may be implemented invarious methods. For convenience' sake in the description, the modesignal MS indicates the first mode when MS is low and indicates thesecond mode when MS is high. A battery current may be in a usual batterycurrent range (i.e., several hundreds of mA) in the first mode and maybe in a micro battery current range (i.e., several mA) in the secondmode.

The controller 140 may determine that the fuel gauge system 100 changesfrom the second mode to the first mode when the mode signal MS transitsfrom high to low. The controller 140 may also enable the first switch110 and then disable the second switch 120 when the fuel gauge system100 changes from the second mode to the first mode. Contrarily, thecontroller 140 may determine that the fuel gauge system 100 changes fromthe first mode to the second mode when the mode signal MS transits fromlow to high. When the fuel gauge system 100 changes from the first modeto the second mode, the controller 140 may also enable the second switch120 after waiting for a desired, or alternatively predetermined timeTdly and disable the first switch 110. The desired, or alternativelypredetermined time Tdly may be variable.

The fuel gauge circuit 150 may measure a battery current flowing in thefirst resistive element 115 and the second resistive element 125. Thefuel gauge circuit 150 may measure the battery current by measuring avoltage difference between both ends of the first resistive element 115and the second resistive element 125.

The fuel gauge circuit 150 may include an amplifier 151 and ananalog-to-digital converter (ADC) 152, as shown in FIG. 2. The amplifier151 may be or include a sense amplifier or a buffer. For convenience inthe description, it is assumed that the amplifier 151 has anamplification (i.e., Vo/Vi) of 1 (i.e., the amplifier 151 may be abuffer). However, the inventive concepts are not restricted to theseexample embodiments.

The amplifier 151 may be connected to respective ends of the first andsecond resistive elements 115 and 125. Here, both ends of the first andsecond resistive elements 115 and 125 may be a measurement node NM and abattery node NB. The amplifier 151 may sense potentials at the ends ofthe first and second resistive elements 115 and 125 and output a voltagedifference Vd between both ends of the first and second resistiveelements 115 and 125 to the ADC 152.

In the first mode, the voltage difference Vd output from the amplifier151 to the ADC 152 may be the first potential difference V1. The firstpotential difference V1 is calculated using Equation 1 and may be thesame as a potential difference created when a battery current flows inthe first resistive element 115. In the example embodiments illustratedin FIG. 2, the first potential difference V1 may be a potential of thebattery node NB less a potential of the measurement node NM. Since thebattery current does not flow in the second resistive element 125 in thefirst mode, the potential of the measurement node NM may be the same asthe potential of a central node NC. Accordingly, the first potentialdifference V1 may be the potential of the battery node NB less thepotential of the central node NC.

In the second mode, the voltage difference Vd output from the amplifier151 to the ADC 152 may be the second potential difference V2. The secondpotential difference V2 is calculated using Equation 2 and may be thesame as a potential difference created when a battery current flows inthe first resistive element 115 and the second resistive element 125. Inthe example embodiments illustrated in FIG. 2, the second potentialdifference V2 may be the potential of the battery node NB less thepotential of the measurement node NM. Since the battery current flows inthe first resistive element 115 and the second resistive element 125 inthe second mode, the potential of the measurement node NM is differentfrom the potential of the central node NC. Accordingly, the secondpotential difference V2 may be the sum of the potential of the batterynode NB less the potential of the central node NC and the potential ofthe central node less the potential of the measurement node NM.

The ADC 152 may convert the voltage difference Vd received from theamplifier 151 into a digital signal. The ADC 152 may output the digitalsignal to the AP or the platform logic.

The charging circuit 180 may charge the battery 130 using an externalpower supply (not shown). When the external power supply is connected tothe charging circuit 180, the battery 130 may be charged. At this time,a battery current may flow in a direction opposite to a direction inwhich a battery current flows when the external power supply is notconnected.

FIG. 3 is a detailed block diagram of a fuel gauge system 100A accordingto other example embodiments of the inventive concepts. FIG. 4 is atiming chart showing the operation of the fuel gauge system 100Aillustrated in FIG. 3. The operation of the fuel gauge system 100Aillustrated in FIG. 3 is similar to or the same as the operation of thefuel gauge system 100 illustrated in FIG. 2. Thus, the description belowwill be focused on differences between the fuel gauge systems 100 and100A.

Referring to FIGS. 3 and 4, the fuel gauge system 100A may include afirst resistive element 115A, a second resistive element 125A, a firstswitch 110A, a second switch 120A, a controller 140A, a fuel gaugecircuit 150A, a level detector 160A, and a charging circuit 180A. Thefuel gauge system 100A may automatically operate the switches 110A and120A according to a battery current.

The controller 140A may output the first switching signal Q1 to thefirst switch 110A and the second switching signal Q2 to the secondswitch 120A to control the turning on/off of the first and secondswitches 110A and 120A for a substantially accurate measurement ofbattery current. Unlike the controller 140 illustrated in FIG. 2 whichreceives the mode signal MS from the AP or the platform logic, thecontroller 140A illustrated in FIG. 3 may receive the mode signal MSfrom the level detector 160A.

When the mode signal MS transits from high to low, that is, when thefuel gauge system 100A changes from the second mode to the first mode;the controller 140A may enable the first switch 110A and then disablethe second switch 120A. Contrarily, when the mode signal MS transitsfrom low to high, that is, when the fuel gauge system 100A changes fromthe first mode to the second mode, the controller 140A may enable thesecond switch 120A after waiting for the desired, or alternativelypredetermined time Tdly, and disable the first switch 110A. The desired,or alternatively predetermined time Tdly may be variable.

The controller 140A may output scaling information SI to a scaler 153Abased on the mode signal MS received from the level detector 160A. Forinstance, it is assumed that the resistance value R1 of the firstresistive element 115A is about 10 mΩ and the resistance value R2 of thesecond resistive element 125A is about 10Ω. When the controller 140Areceives a mode signal MS that is low, the controller 140A may outputthe scaling information SI corresponding to 1 to the scaler 153A.Contrarily, when the controller 140A receives a mode signal MS that ishow, the controller 140A may output the scaling information SIcorresponding to 1000 to the scaler 153A. The scaling information SI maydependent on the resistance values R1 and R2 of the first and secondresistive elements 115A and 125A, and may be desired or alternativelypredetermined, and variable.

The controller 140A may output the mode signal MS received from thelevel detector 160A to an AP (not shown) or a platform logic (notshown).

The level detector 160A may be a circuit which measures a batterycurrent. The level detector 160A may be connected to both ends of thefirst and second resistive elements 115A and 125A. Here, the both endsof the first and second resistive elements 115A and 125A may be themeasurement node NM and the battery node NB, respectively.

The level detector 160A may detect potentials of both ends of the firstand second resistive elements 115A and 125A. The level detector 160A maydetermine whether the fuel gauge system 100A is in the first mode or inthe second mode based on a potential difference between both ends of thefirst and second resistive elements 115A and 125A. For instance, whenthe potential difference between both ends of the first and secondresistive elements 115A and 125A is greater than a first threshold VT1,the level detector 160A may determine that the fuel gauge system 100A isin the first mode. When the potential difference between both ends ofthe first and second resistive elements 115A and 125A is less than asecond threshold VT2, the level detector 160A may determine that thefuel gauge system 100A is in the second mode. The first threshold VT1may be greater than the second threshold VT2. The level detector 160Amay output the mode signal MS to the controller 140A.

The fuel gauge circuit 150A may include an amplifier 151A, an ADC 152A,and the scaler 153A. The amplifier 151A may be connected to both ends ofthe respective first and second resistive elements 115A and 125A. Here,both ends of the first and second resistive elements 115A and 125A maybe the measurement node NM and the battery node NB. The amplifier 151Amay sense potentials at both ends of the first and second resistiveelements 115A and 125A and output the voltage difference Vd between bothends of the first and second resistive elements 115A and 125A to the ADC152A.

The ADC 152A may convert the voltage difference Vd received from theamplifier 151A into a digital signal. The ADC 152A may output thedigital signal to the scaler 153A.

The scaler 153A may receive the scaling information SI from the ADC152A. The scaler 153A may also receive the digital signal from the ADC152A. The scaler 153A may scale the digital signal based on the scalinginformation SI. The scaler 153A may output a scaled digital signal to anAP (not shown) or a platform logic (not shown).

For instance, when the scaler 153A receives a digital signalcorresponding to 4 and the scaling information SI corresponding to 1,the scaler 153A may scale 1 to 4 and output a digital signalcorresponding to 4. When the scaler 153A receives a digital signalcorresponding to about 0.004 and the scaling information SIcorresponding to 1000, the scaler 153A may scale about 1000 to about0.004 and output a digital signal corresponding to 4.

The operations and functions of the first resistive element 115A, thesecond resistive element 125A, the first switch 110A, the second switch120A, and the charging circuit 180A illustrated in FIG. 3 are the sameas those of the first resistive element 115, the second resistiveelement 125, the first switch 110, the second switch 120, and thecharging circuit 180 illustrated in FIG. 2. Thus, the description of thefirst resistive element 115A, the second resistive element 125A, thefirst switch 110A, the second switch 120A, and the charging circuit 180Awill be omitted to avoid redundancy.

The voltage difference Vd output from the amplifier 151A, the modesignal MS, the first switch 110A, and the second switch 120A will bedescribed with reference to FIG. 4 on the assumption that the batterycurrent Ibat decreases and increases over time. As the battery currentIbat decreases, the voltage difference Vd corresponding to the potentialdifference between both ends of the first and second resistive elements115A and 125A created by the flow of the battery current Ibat alsodecreases. Here, both ends of the first and second resistive elements115A and 125A may be the measurement node NM and the battery node NB. Atthis time, the fuel gauge system 100A may be in the first node.

Since the first switch 110A has been enabled and the second switch 120has been disabled, the battery current Ibat flows only in the firstresistive element 115A. Accordingly, the voltage difference Vd outputfrom the amplifier 151A is the same as the potential difference betweenboth ends of the first resistive element 115A. When the voltagedifference Vd is less than the second threshold VT2, the fuel gaugesystem 100A enters the second mode. At this time, the controller 140Amay wait for the desired, or alternatively predetermined time Tdly, andenable the second switch 120A and disable the first switch 110A, asdescribed above, in order to prevent malfunction.

The controller 140A staggers the enabling of the second switch 120A andthe disabling of the first switch 110A in order to prevent an erroroccurring when switches are disabled at substantially the same time. Forinstance, when the controller 140A enables the second switch 120A priorto the first switch 110A, the battery current Ibat flows only in thefirst resistive element 115A and the voltage difference Vd does notchange discretely. When the controller 140A disables the first switch110A thereafter, the battery current Ibat flows in both the first andsecond resistive elements 115A and 125A and the voltage difference Vdchanges discretely.

As the battery current Ibat increases, the voltage difference Vd outputfrom the amplifier 151A due to the flow of the battery current Ibat alsoincreases. At this time, it is assumed that the fuel gauge system 100Ais in the second node. In other words, since the first switch 110A hasbeen disabled and the second switch 120 has been enabled, the batterycurrent Ibat flows in both the first and second resistive elements 115Aand 125A.

When the voltage difference Vd is greater than the first threshold VT1,the fuel gauge system 100A enters the first mode. At this time, thecontroller 140A may enable the first switch 110A and disable the secondswitch 120A, as described above. The controller 140A may wait for adesired, or alternatively predetermined time as in the second mode, butthere is substantially no wait time in the description below.

The controller 140A staggers the enabling of the first switch 110A andthe disabling of the second switch 120A in order to substantiallyprevent an error occurring when switches are disabled at the same time.When the controller 140A first enables the first switch 110A, thebattery current Ibat flows only in the first resistive element 115A andthe voltage difference Vd changes discretely. Thereafter, when thecontroller 140A disables the second switch 120A, the battery currentIbat flows in the first resistive element 115A continually and thevoltage difference Vd changes continuously.

FIG. 5 is a detailed block diagram of a fuel gauge system 100B accordingto example embodiments of the inventive concepts. The operation of thefuel gauge system 100B illustrated in FIG. 5 is similar to or the sameas the operation of the fuel gauge system 100 illustrated in FIG. 2.Thus, the description below will be focused on differences between thefuel gauge systems 100 and 100B.

Referring to FIG. 5, the fuel gauge system 100B may include a firstresistive element 115B, a second resistive element 125B, a first switch110B, a second switch 120B, a controller 140B, a fuel gauge circuit150B, a first charging circuit 180B, and a second charging circuit 190B.The first charging circuit 180B and the second charging circuit 190B mayperform substantially the same functions as the charging circuit 180illustrated in FIG. 2.

The second charging circuit 190B may charge a battery 130B using adifferent external power supply (not shown) than the first chargingcircuit 180B uses. The second charging circuit 190B may charge thebattery 130B through a different path than the first charging circuit180B charges. The second charging circuit 190B may be connected, forexample directly connected to a node, i.e., the central node NC betweenthe first resistive element 115B and the second resistive element 125B.The second charging circuit 190B may be used for quick charge.

The operations and functions of the first resistive element 115B, thesecond resistive element 125B, the first switch 110B, the second switch120B, the controller 140B, and the fuel gauge circuit 150B illustratedin FIG. 5 are substantially the same as the operations and functions ofthe first resistive element 115, the second resistive element 125, thefirst switch 110, the second switch 120, the controller 140, and thefuel gauge circuit 150 illustrated in FIG. 2. Thus, the description ofthe first resistive element 115B, the second resistive element 125B, thefirst switch 110B, the second switch 120B, the controller 140B, and thefuel gauge circuit 150B will be omitted to avoid redundancy.

FIG. 6 is a detailed block diagram of a fuel gauge system 100C accordingto example embodiments of the inventive concepts. The operation of thefuel gauge system 100C illustrated in FIG. 6 is similar to or the sameas the operation of the fuel gauge system 100 illustrated in FIG. 2.Thus, the description below will be focused on differences between thefuel gauge systems 100 and 100C.

Referring to FIG. 6, the fuel gauge system 100C may include a firstresistive element 115C, a second resistive element 125C, a first switch110C, a second switch 120C, a controller 140C, a fuel gauge circuit150C, and a charging circuit 180C. The first resistive element 115C maybe placed between a battery 130C and the ground.

The fuel gauge circuit 150C may measure a battery current flowing in thefirst resistive element 115C and the second resistive element 125C. Thefuel gauge circuit 150C may include a first amplifier 151-1, a secondamplifier 151-2, a first ADC 152-1, and a second ADC 152-2. The fuelgauge circuit 150C may be connected to both ends of the first resistiveelement 115C and both ends of the second resistive element 125C.

The first amplifier 151-1 may be connected to both ends of the firstresistive element 115C, may sense potentials of both ends of the firstresistive element 115C, and may output a first voltage difference Vd1corresponding to a potential difference between both ends of the firstresistive element 115C to the first ADC 152-1. The second amplifier151-2 may be connected to both ends of the second resistive element125C, may sense potentials of both ends of the second resistive element125C, and may output a second voltage difference Vd2 corresponding to apotential difference between both ends of the second resistive element125B to the second ADC 152-2. The second voltage difference Vd2 outputfrom the second amplifier 151-2 to the second ADC 152-2 may be 0 in thefirst mode.

The first ADC 152-1 may convert the first voltage difference Vd1received from the first amplifier 151-1 into a first digital signal. Thesecond ADC 152-2 may convert the second voltage difference Vd2 receivedfrom the second amplifier 151-2 into a second digital signal. The firstand second ADCs 152-1 and 152-2 may respectively output the firstdigital signal and the second digital signal to an AP (not shown) or aplatform logic (not shown).

The operations and functions of the second resistive element 125C, thefirst switch 110C, the second switch 120C, the controller 140C, and thecharging circuit 180C illustrated in FIG. 6 are substantially the sameas the operations and functions of the second resistive element 125, thefirst switch 110, the second switch 120, the controller 140, and thecharging circuit 180 illustrated in FIG. 2. Thus, the description of thesecond resistive element 125C, the first switch 110C, the second switch120C, the controller 140C, and the charging circuit 180C will be omittedto avoid redundancy.

FIG. 7 is a detailed block diagram of a fuel gauge system 100D accordingto example embodiments of the inventive concepts. The operation of thefuel gauge system 100D illustrated in FIG. 7 is similar to or the sameas the operation of the fuel gauge system 100 illustrated in FIG. 2.Thus, description will be focused on differences between the fuel gaugesystems 100 and 100D.

Referring to FIG. 7, the fuel gauge system 100D may include a firstswitch 110D, a second switch 120D, a controller 140D, a fuel gaugecircuit 150D, and a charging circuit 180D. The first switch 110D may beconnected in series to a battery 130D and the second switch 120D may beconnected in parallel to the first switch 110D.

The first switch 110D may be enabled when the first switching signal Q1is low and the second switch 120D may be enabled when the secondswitching signal Q2 is low. The first switch 110D may be a transistorthat functions as a first resistor when it is enabled. The second switch120D may be a transistor that functions as a second resistor when it isenabled. A second resistance value of the second resistor may be greaterthan a first resistance value of the first resistor.

The controller 140D may output the first switching signal Q1 to thefirst switch 110D and the second switching signal Q2 to the secondswitch 120D to control on/off of the first and second switches 110D and120D for a substantially accurate measurement of a battery current.

The fuel gauge circuit 150D may be connected to both ends of the firstswitch 110D or both ends of the second switch 120D. The fuel gaugecircuit 150D may include an amplifier 151D and an ADC 152D.

The amplifier 151D may receive potentials from both ends of the firstswitch 110D or from both ends of the second switch 120D. The amplifier151D may sense the potentials from both ends of the first switch 110D orfrom both ends of the second switch 120D and may output the voltagedifference Vd corresponding to the potential difference between bothends to the ADC 152D.

The ADC 152D may convert the voltage difference Vd received from theamplifier 151D into a digital signal. The ADC 152D may output thedigital signal to an AP (not shown) or a platform logic (not shown).

The operations and functions of the controller 140D, the fuel gaugecircuit 150D, and the charging circuit 180D illustrated in FIG. 7 arethe same as the operations and functions of the controller 140, the fuelgauge circuit 150, and the charging circuit 180 illustrated in FIG. 2.Thus, the description of the controller 140D, the fuel gauge circuit150D, and the charging circuit 180D will be omitted to avoid redundancy.

Furthermore, a program (computer-readable program) according to anexample embodiment of the inventive concepts may be a PC-based programor an application dedicated to a mobile terminal. Accordingly, anapplication related to current measurement may be implemented in aprogram form that operates independently of a particular application. Itmay be implemented to allow an operation on the particular application.

In addition, according to an example embodiment of inventive concepts,an application associated with a server system for measuring current maybe performed by controlling the user terminal. For example, thisapplication may execute one or more processors configured to perform oneor more aspects of the features described herein.

The units (or devices) described herein may be implemented usinghardware components, at least one processor, such as the applicationprocessor AP included in the plurality of chips 200, executing softwarecomponents, and/or a combination thereof. For example, the portableelectronic device 10 may be implemented by processing circuitry such asa processor, a controller, an arithmetic logic unit (ALU), a digitalsignal processor, a microcomputer, a field programmable gate array(FPGA), a programmable logic unit, a microprocessor or any other devicecapable of responding to and executing instructions in a defined manner.A processing device may run an operating system (OS) and one or moresoftware applications that run on the OS. The processing device also mayaccess, store, manipulate, process, and create data in response toexecution of the software. For the sake of easy understanding, anembodiment of the inventive concepts is exemplified as one processingdevice is used; however, one skilled in the art will appreciate that aprocessing device may include multiple processing elements and multipletypes of processing elements. For example, the application processor(AP) included in the plurality of chips 200 may include multipleprocessors or a processor and a controller. In addition, otherprocessing configurations are possible, such as parallel processors.

The software may include a computer program, a piece of code, aninstruction, or some combination thereof, for independently orcollectively instructing or configuring the processing device to operateas desired. Software and/or data may be embodied permanently ortemporarily in any type of machine, component, physical or virtualequipment, computer storage medium or device, or in a propagated signalwave capable of providing instructions or data to or being interpretedby the processing device. The software also may be distributed overnetwork coupled computer systems so that the software is stored andexecuted in a distributed fashion. In particular, the software and datamay be stored by one or more computer readable recording mediums.

The methods according to example embodiments may be implemented in theformat of program instruction executable through various processingcircuitry and may be recorded in a computer-readable medium. Thecomputer-readable medium may also include program instructions, datafiles, data structures, and the like independently or in the format ofcombination. The program instructions recorded in the medium may bethose specially designed and constructed for the embodiment or may bewell-known and available to those skilled in the computer software arts.Examples of the computer-readable medium may include magnetic media suchas hard disks, floppy disks, and magnetic tape; optical media such as CDROM disks and DVD; magneto-optical media such as floptical disks; andhardware devices that are specialized to store and perform programinstructions, such as read-only memory (ROM), random access memory(RAM), flash memory, and the like. Examples of program instructions mayinclude both machine code produced by a compiler and high-level codeexecuted by the computer using an interpreter. The described fuel gaugesystem 100 may be configured as one or more modules or units to performthe operations of the above-described example embodiments, and viceversa.

As described above, according to example embodiments of the inventiveconcepts, a fuel gauge system uses a plurality of resistive elements ina portable electronic device using a battery, thereby increasing ameasuring sensitivity and substantially accurately measuring a batterycurrent. Accordingly, when a micro battery current (i.e., less thanabout 1 mA) flows, the battery current can be more accurately measured.In addition, a delay is set in the operation timing of a plurality ofswitches, so that an error that may occur when all of the switches areturned off is prevented.

While the inventive concepts has been particularly shown and describedwith reference to example embodiments thereof, it will be understood bythose of ordinary skill in the art that various changes in forms anddetails may be made therein without departing from the spirit and scopeof the inventive concepts as defined by the following claims.

What is claimed is:
 1. A fuel gauge system for measuring an amount ofcurrent in a battery, the fuel gauge system comprising: a firstresistive element connected in series to the battery; a second resistiveelement connected in series to the first resistive element; a firstswitch connected in parallel to the second resistive element andconfigured to control a current flowing in the second resistive element;a second switch connected in series to the second resistive element andconfigured to control the current flowing in the second resistiveelement; a controller configured to output a first switching signal tothe first switch and output a second switching signal to the secondswitch; and a fuel gauge circuit configured to measure a battery currentflowing in the first resistive element and in the second resistiveelement.
 2. The fuel gauge system of claim 1, wherein the firstresistive element is directly connected to the second resistive element,and the fuel gauge circuit includes: an amplifier configured to sensepotentials of both ends of the first and second resistive elements; andan analog-to-digital converter configured to output a digital signalbased on a voltage difference received from the amplifier.
 3. The fuelgauge system of claim 1, wherein the battery is between the firstresistive element and the second resistive element, and the fuel gaugecircuit includes: a first amplifier configured to sense potentials ofboth ends of the first resistive element; and a second amplifierconfigured to sense potentials of both ends of the second resistiveelement.
 4. The fuel gauge system of claim 2, wherein the controller isconfigured to enable the first switch and to disable the second switchwhen a mode signal corresponding to a first mode is received, and thecontroller is configured to enable the second switch after a desiredtime and to disable the first switch when a mode signal corresponding toa second mode is received.
 5. The fuel gauge system of claim 4, furthercomprising a level detector configured to receive potential values ofboth ends of the first resistive element and potential values of bothends of the second resistive element, configured to detect a level ofthe battery current, and configured to output the mode signal to thecontroller.
 6. The fuel gauge system of claim 5, wherein the fuel gaugecircuit further comprises a scaler configured to scale the digitalsignal received from the analog-to-digital converter according toscaling information received from the controller, and the controller isconfigured to output a desired scaling information to the scaleraccording to the mode signal.
 7. The fuel gauge system of claim 2,further comprising: a first charging circuit connected to the firstswitch; and a second charging circuit connected to the first resistiveelement through a different path than a path connecting the firstcharging circuit to the first resistive element.
 8. A portableelectronic device, the portable electronic device comprising: a fuelgauge system configured to measure an amount of current in a battery;and a plurality of chips connected to the fuel gauge system, wherein thefuel gauge system includes: a first resistive element connected inseries to the battery; a second resistive element connected in series tothe first resistive element; a first switch connected in parallel to thesecond resistive element and configured to control a current flowing inthe second resistive element; a second switch connected in series to thesecond resistive element and configured to control the current flowingin the second resistive element; a controller configured to output afirst switching signal to the first switch and to output a secondswitching signal to the second switch; and a fuel gauge circuitconfigured to measure a battery current flowing in the first resistiveelement and in the second resistive element.
 9. The portable electronicdevice of claim 8, wherein the first resistive element is directlyconnected to the second resistive element, and the fuel gauge circuitincludes: an amplifier configured to sense potentials of both ends ofthe first and second resistive elements; and an analog-to-digitalconverter configured to output a digital signal based on a voltagedifference received from the amplifier.
 10. The portable electronicdevice of claim 9, wherein the controller is configured to enable thefirst switch and to disable the second switch when a mode signalcorresponding to a first mode is received, and the controller isconfigured to enable the second switch after waiting for a desired timeand to disable the first switch when a mode signal corresponding to asecond mode is received.
 11. The portable electronic device of claim 10,wherein the fuel gauge system further comprises a level detectorconfigured to receive potential values of both ends of the firstresistive element and potential values of both ends of the secondresistive element, to detect a level of the battery current, and tooutput the mode signal to the controller.
 12. The portable electronicdevice of claim 11, wherein the fuel gauge circuit further comprises ascaler configured to scale the digital signal received from theanalog-to-digital converter according to scaling information receivedfrom the controller, and the controller is configured to output adesired scaling information to the scaler according to the mode signal.13. A fuel gauge system comprising: a first switch connected in seriesto a first resistor and to a battery, and in parallel to a secondresistor; a second switch connected in series to the first and secondresistors, and in parallel to the first switch; and a fuel gauge circuitconnected in parallel to the first and second resistors and configuredto measure a battery current flowing in the first resistor and in thesecond resistor.
 14. The fuel gauge system of claim 13, furthercomprising a controller configured to output a first switching signal tothe first switch and to output a second switching signal to the secondswitch.
 15. The fuel gauge system of claim 13, wherein the first switchis a first transistor configured to operate as the first resistor whenenabled, and the second switch is a second transistor configured tooperate as the second resistor when enabled, the second transistorhaving a greater resistance than the first transistor.
 16. The fuelgauge system of claim 14, further comprising: an amplifier configured tosense potentials of opposite ends of the first and second resistors; andan analog-to-digital converter configured to output a digital signalbased on a voltage difference received from the amplifier.
 17. The fuelgauge system of claim 16, wherein the amplifier comprises: a firstamplifier configured to sense potentials of opposite ends of the firstresistor; and a second amplifier configured to sense potentials ofopposite ends of the second resistor.
 18. The fuel gauge system of claim16, further comprising: a level detector configured to receive potentialvalues of opposite ends of the first resistor and potential values ofopposite ends of the second resistor, configured to detect a level ofthe battery current, and configured to output one of a first mode signaland a second mode signal to the controller.
 19. The fuel gauge system ofclaim 18, further comprising: a scaler configured to scale the digitalsignal received from the analog-to-digital converter according toscaling information received from the controller, the controller beingconfigured to output a desired scaling information to the scaleraccording to one of the first mode signal and the second mode signal.20. The fuel gauge system of claim 13, further comprising: a firstcharging circuit connected to the first switch; and a second chargingcircuit connected to the first resistor through a different path than apath connecting the first, charging circuit to the first resistor.